beat vs throb

beat and throb both are nouns.

Word	Noun	Adjective	Verb	Adverb
beat	Yes	Yes	Yes	No
throb	Yes	No	Yes	No

As nouns, throb is a hyponym of beat; that is, throb is a word with a more specific, narrower meaning than beat:

beat: the rhythmic contraction and expansion of the arteries with each beat of the heart
throb: an instance of rapid strong pulsation (of the heart)

Other hyponyms of beat include diastole, systole, pounding, throbbing.

As verbs, throb is a hyponym of beat; that is, throb is a word with a more specific, narrower meaning than beat:

Other hyponyms of beat include pulsate, pulse, flutter, palpitate, thrash, flap.

beat (noun)	throb (noun)
the act of beating to windward; sailing as close as possible to the direction from which the wind is blowing	an instance of rapid strong pulsation (of the heart)
a stroke or blow	a deep pulsating type of pain
a regular rate of repetition
the basic rhythmic unit in a piece of music
(prosody) the accent in a metrical foot of verse
the rhythmic contraction and expansion of the arteries with each beat of the heart
the sound of stroke or blow
a regular route for a sentry or policeman
a member of the beat generation; a nonconformist in dress and behavior
a single pulsation of an oscillation produced by adding two waves of different frequencies; has a frequency equal to the difference between the two oscillations

beat (adjective)	throb (adjective)
very tired

beat (verb)	throb (verb)
wear out completely	tremble convulsively, as from fear or excitement
be a mystery or bewildering to	expand and contract rhythmically; beat rhythmically
come out better in a competition, race, or conflict	pulsate or pound with abnormal force
beat through cleverness and wit
hit repeatedly
give a beating to; subject to a beating, either as a punishment or as an act of aggression
stir vigorously
strike (a part of one's own body) repeatedly, as in great emotion or in accompaniment to music
strike (water or bushes) repeatedly to rouse animals for hunting
shape by beating
make by pounding or trampling
produce a rhythm by striking repeatedly
move rhythmically
sail with much tacking or with difficulty
move with a flapping motion
indicate by beating, as with the fingers or drumsticks
move with a thrashing motion
move with or as if with a regular alternating motion
make a rhythmic sound
make a sound like a clock or a timer
glare or strike with great intensity
avoid paying
be superior